Ординатура / Офтальмология / Учебные материалы / Primary Retinal Detachment Options for Repair Kreissig Springer

Paracentesis of the anterior chamber is a controversial step in the procedure. Some surgeons routinely soften all eyes prior to injection, while some perform the step only rarely. Others perform paracentesis after the gas injection as required by the IOP. Paracentesis is less important with one-step procedures where the scleral depression associated with cryopexy softens the globe and in cases where smaller volumes of expansile gas are utilized. Paracentesis is most often required in two-step (laser) cases and when injecting large gas volumes. The step is performed by entering the anterior chamber with a 30-gauge needle affixed to a 1-ml syringe without the plunger.Aqueous humor is allowed to passively egress until the anterior chamber shallows. A sterile cotton tip applicator is rolled onto the needle track as the needle is withdrawn to avoid additional fluid egress. Care is given to avoid needle tip-lens touch. Paracentesis is contraindicated in aphakic and pseudophakic patients with vitreous prolapse into the anterior chamber.

Gas injection is the most important component step of PR, and many postoperative complications can be avoided with proper technique. The surgeon utilizes the indirect ophthalmoscope for lighting, visualization of needle tip, and later to assess gas location and patency of the central retinal artery. The patient is placed in a recumbent position with the head tilted 45° away from the operative eye. This places the temporal pars plana as the highest point on the globe. The injection is given 4 mm posterior to the limbus, usually in the temporal quadrant, unless the retina is bullously detached in the area. The needle tip is advanced into the mid-vitreous cavity, under direct visualization with the indirect ophthalmoscope to penetrate the anterior hyaloid face. Then the needle is withdrawn until just the tip is visible, 2–3 mm through the pars plana epithelium. Gas is injected in a brisk but controlled manner. Following gas injection, the head is carefully rotated to a neutral position in order to move gas away from the injection site and avoid egress of gas out the needle track. A sterile cotton tip applicator is rolled over the track as the needle is removed to minimize

gas reflux. Following gas injection, the bubble size and position are assessed, and central retinal artery perfusion is assured with indirect ophthalmoscopy.

IOP rises abruptly in most patients who receive greater than 0.2 ml gas. The IOP is checked immediately following gas placement. Frequently, pressure measurements fall in the 50–70 mmHg range. If the patient has a normal aqueous outflow mechanism, he or she can be monitored with serial tonometry every 10–15 min, which frequently demonstrates a return to more normal pressures over 15–30 min. Paracentesis, as noted above, may be performed before or after gas injection (or both) to normalize IOP. The pressure should be near normal and the central retinal artery perfused prior to the patient’s departure.

Postoperatively, an antibiotic/steroid combination ointment is placed in the eye, and a patch is applied. An arrow is drawn on the patch, such that the arrow points straight at the ceiling when the patient is properly positioned (break in uppermost position of the globe). The patient and caregiver are reminded of the required position with special emphasis on the need for compliance, especially at night while asleep. The patient returns for follow-up on the first postoperative day. The SRF is usually substantially improved or entirely resolved. The gas bubble size and location are assessed, and the IOP is measured. Laser may be performed as part of a staged procedure (see above).For patients with extensive cryopexy, antibiotic and steroid drops may be prescribed for a few days. The importance of proper position is stressed yet again. In cases where there is little or no change in the SRF, patient compliance is reassessed, and an exhaustive exam for new or missed breaks is undertaken. In the typical scenario where the fluid is substantially better, the patient is re-examined on the third to fifth postoperative day.

Complications: Prevention and Management

Intraoperative

There are limited complications associated with the use of PR. The most common set of problems arise from difficulties with the gas bubble itself, particularly migration into unintended potential spaces. Subconjunctival gas is the most common location,being reported in 0–10% of cases (Table 4.5) [3, 9–11]. Gas has also been reported in the subretinal space (0–4%) [12–15], anterior to the anterior hyaloid (0–9%) [11, 13, 14], in the suprachoroidal space (0–5%) [13–15],and exterior to pars plana epithelium (0–1%) [9]. Following injection, the gas inside the eye may form multiple small “fish egg” bubbles rather than a single large one. Fish eggs provide inadequate tamponade, as they do not occlude breaks with the same efficiency as a large smooth meniscus. This same feature also makes them more likely to migrate into the subretinal space. Multiple small bubble formation can usually be avoided through proper injection technique (see above).When this does occur,the eye may be forcefully tapped or “thumped” with the surgeon’s finger, which can lead to coalescence (a technique that has been described,

Table 4.5. Reported intraoperative complications

though perhaps not employed by all). If this maneuver fails, the patient should be positioned face down for 6–12 h in order to prevent subretinal migration. During this time period, fish eggs inevitably unite to form the desired, effective single large bubble. Migration of bubbles, especially with expansile gas, into the subretinal space is a substantial complication. This event can be avoided by visualizing the needle within the vitreous cavity prior to injection, achieving a single bubble rather than fish eggs, and by avoiding case selection involving large tears with severe traction. Once gas enters the subretinal space, it may be managed by maneuvering the patient’s head and eye in such a way that it rolls the bubble back through the tear into the vitreous cavity. This is often aided by simultaneous scleral depression. These maneuvers are often unsuccessful, and vitrectomy surgery is necessary for removal. During vitrectomy, the bubble will displace the detached retina anteriorly toward the lens – making infusion line placement, sclerotomy incisions, and instrument entry into the eye problematic. A small retinotomy performed with the vitreous cutter probe located at the most anterior, superior pole of the subretinal bubble usually works well for evacuation.

Postoperative

The most common postoperative complication of PR is new and/or missed retinal breaks (Table 4.6) [3, 9, 11–18]. Most of these are discovered during the first postoperative month, with between 61% and 86% being identified during this time period [19, 20]. Of new and/or missed breaks, 76% occur in the superior two-thirds of the retina. They almost invariably occur anterior to the equator and are more common in pseudophakic or aphakic eyes [20]. Missed breaks can be avoided by performing a very thorough preoperative retinal examination. The authors have found that a 78D or 90D exam of the peripheral retina is invaluable for discovering small breaks preoperatively. Additionally, cases with media opacities,

such as sector or spoke cortical cataracts, peripheral capsular opacification, and vitreous hemorrhage, which preclude a clear view,may be less well suited to PR. The risk of new break formation is minimized using prophylactic treatment of at-risk lesions, such as lattice patches,cystic tufts,and meridional complexes,with laser prior to gas injection. Consideration should be given to prophylactic 360° laser at the vitreous base, which has been reported to lower the rate of new/missed breaks and increase surgical success [14]. Delayed resorption of SRF is encountered in between 0% and 6% of cases [10, 14, 16]. In most instances, the original detachment was subacute or chronic, and the SRF was shifted away from the original break, trapping it in the subretinal space.

Additional reported posterior segment complications included epiretinal membrane (ERM) formation in 0% to 11% of cases [9, 11–17],PVR in 3% to 13% [3,9,11–18],cystoid macular edema (CME) in 0% to 8% [14, 18], macular hole in 0% to 3% [13–15, 17], anterior ischemic optic neuropathy in four cases [14, 17], and endophthalmitis in one case [13].

Late anterior segment complications include cataract formation.Although lens injury during injection is rare,late cataract presumably due to gas-lens touch is much more common. Cataract is reported in 0% to 20% of cases [11, 13–15, 17, 18], with rates depend-

ing on type and amount of gas used as well as duration of followup postoperatively.

New Possibilities

Surgeons continue to push the limits for detachments amenable to treatment using PR. Detachments with breaks in more than one quadrant may be repaired by augmenting the bubble size via a second injection on the first or second postoperative day, or by flattening one break over a 72-h period, then changing patient positioning to address the second area in another quadrant [21]. The treatment of detachments with large breaks has been controversial. Gas is more prone to migrate into the subretinal space, and the arc of contact may not be broad enough to tamponade the entire break. Nevertheless,reports exist of the successful use of PR for RRDs due to giant retinal tear (4 of 5–80%), retinal dialysis (4 of 4–100%), and other large breaks [22–24]. These reports demonstrate that PR can be effective for cases with large breaks if they are located superiorly and lack significant vitreoretinal traction. Pneumatic retinopexy has generally been avoided for RRD with breaks in the inferior 4 clock hours of the fundus. Inverted PR has been reported in phakic detachments. Utilizing 8 h of “head dangling” positioning followed by laser retinopexy or cryopexy, the single surgery reattachment rate was 9 of 11 (82%) [25]. It is evident that although PR has an“ideal”scenario for its chief indication, the technique is more widely applicable in certain select cases for those with multiple breaks, large breaks, and even breaks located in the inferior four clock hours.

Results

Anatomic Results of PR

The reported primary anatomic success rates of PR vary widely in published series, ranging from 61% to 90% with an overall single procedure combined rate of 75.5% – 918/1,215 cases (Table 4.7) [3, 9–18, 26–29]. There does not appear to be a difference between the selection of tamponade agents with respect to anatomic outcome – with filtered air, SF6, and C3F8 having similar reported results. There is no trend toward higher success rates over time. The 84% primary anatomic success rate reported by Hilton [9] is similar to the reports by Abecia [15] and Eter [28], with success rates of 82% and 86%, respectively. The overall final anatomic (with reoperations) success varies between 87% and 100% in this group of

Table 4.7. Anatomic and visual outcomes

a Macula detached <2 weeks

reports, with a cumulative success rate of 97.4%.When PR fails, the most common second technique employed was SB; however, a number of patients undergo either pars plana vitrectomy (PPV) alone or PPV with SB.

Visual (Functional) Results

The functional results of PR reported in the literature vary widely, so that it is difficult to compare and summarize the data. For those patients with macula-involved detachments, final best-corrected visual acuity greater than or equal to 20/50 was achieved in between 35% and 80% of cases. The wide variation in these numbers probably represents variation in the duration of macular detachment. Studies that categorized detachments of less than 2 weeks of macular involvement tended to have better outcome averages. Overall, most series reported averages for best-corrected visual acuity greater than or equal to 20/50 following macula-involving detachments to be about 65%.

When examining the data for patients without preoperative detachment of the macula, 86% to 88% will have the same or improved best-corrected visual acuity [9, 13]. However, between 12% and 14% of patients will lose two or more lines of best-corrected visual acuity. Surgical failures and complications were the reason for vision loss in most instances.

Reasons for Failure

The causes of anatomic failure following PR have been examined in several series [19, 30]. New retinal breaks are the most commonly cited reason for failure; however, missed pre-existing breaks are commonly grouped together because of the difficulty differentiating the two. New and/or missed breaks occur in between 7% and 33% of reported cases [3, 9, 11–18] and account for 48% to 73% of

surgical failures. Failure to close the initial break and re-opening of the initial break are typically grouped together. This problem is encountered in 5% to14% of cases [13,15] and is responsible for 25% to 51% of surgical failures. PVR occurs postoperatively in 3% to 13% of cases in reported series [3, 9, 10–18], though fortunately, it is a rare cause of failure.

Discussion

Rhegmatogenous retinal detachment is a very heterogeneous disease state, and, as a result, comparison of surgical results of different techniques is difficult. Certainly PR, primary PPV, and SB each have a place in a surgeon’s armamentarium of treatment modalities. The use of PR is limited by anatomic considerations – number, location and size of breaks, chronicity, preoperative PVR, and lens status – while primary PPV and SB techniques can be used for most cases of RRD. Nevertheless, PR has advantages in certain clinical situations.

Advantages of PR

Given an optimal clinical scenario, PR has several advantages over primary PPV and/or SB for the repair of a RRD. Pneumatic retinopexy is usually performed in the office or as a brief procedure in an outpatient surgical facility. In a multicenter trial reported by Tornambe [13], the average number of hospital days including re-operations was 0.6 days for the PR group and 2.7 days for the SB group. The physician spends less time waiting for availability of the operating room, performing the procedure, and performing post-operative hospital rounds. It should be noted, however, that since this publication in 1989, the majority of procedures, including PR, primary PPV, and SB, are now performed in an outpatient setting.